Fluid motor control system and supply and control valve therefor

ABSTRACT

A fluid motor control system having a four-way fluid pressure responsive valve for determining the direction and rate of flow of the motive fluid in response to the positioning of a manually operable double poppet pilot valve selectively operable to controllably vent the downstream slide of selected inlet chamber and outlet chamber fluid pressure responsive valves to predetermine the direction and rate of flow of the motive fluid to the fluid motor.

United States Patent Inventor Harry Sugden, Jr.

Statesboro, Ga.

Appl. No. 728,295

Filed May 10, 1968 Patented June 15, 1971 Assignee Emerson Electric Co.

St. Louis, Mo.

FLUID MOTOR CONTROL SYSTEM AND SUPPLY AND CONTROL VALVE THEREFORReferences Cited UNITED STATES PATENTS 2/1969 Tennis 11516523 2/1969Tennis I I 91/461X 2.321.267 6/1943 Van Der Werff 91/461 X 2,567,0739/1951 Kupiec 91/461 X 2,569,881 10/1951 Davies 91/454 2,583,185 1/1952McLeod 91/461 X 2,911,005 11/1959 Adelson 91/454X 3,411,536 11/1968Tennis 137/596.15 3,433,131 3/1969 Soyland et a1. 91/461 X 3,332,4407/1967 Brakebill 137/6275 Primary Examiner-Martin P. Schwadron AssistantExaminer Irwin C. Cohen Attorney-Strauch, Nolan, Neale, Nies & KurzABSTRACT: A fluid motor control system having a four-way fluid pressureresponsive valve for determining the direction and rate of flow of themotive fluid in response to the positioning of a manually operabledouble poppet pilot valve selectively operable to controllably vent thedownstream slide of selected inlet chamber and outlet chamber fluidpressure responsive valves to predetermine the direction and rate offlow of the motive fluid to the fluid motor.

I l l F'i 1 I 48 4 I /83 ,BI I 4? 4; l I 1 l 37 5| 1 .5| 5| I 49 37 1 3sso I33 79 1 36 I1 I 61 54 V 55 49 x20 63 7|-. A i

f 35 r B3 33 1 79 w 79 i 43 V 62 46 V I 62 45 i 44 v 44 9 3 43 v5 49":1: I 34 a 49 I ,s 49 32 I I. ,1 I 64 29 5'2 so 53 29 28 1 26 f n, 1 8L PATENTEU JUNISISYI 35 45 9 SHEET 1 []F 4 i 1. N a W INVEN TOR HARRYSUGDEN JR.

ATTORNEYS PATENTEDJUHISIH?! 3584539 sum w UF 4 INVENTOP? HARRY SUGDENJR.

M/wM

ATTOQNEYQ FLUID MOTOR CONTROL SYSTEM AND SUPPLY AND CONTROL VALVETHEREFOR BACKGROUND OF INVENTION The present invention is directed tothe improvement and compacting of the control valving employed tooperate fluid motors of the type disclosed in U.S. Pat. No. 2,913,990 ofC.R. Taylor issued Nov. 24, 1959. In the operation of such motors, ithas been customary to employ several valves for directing andcontrolling the rate of flow of the motive fluid. Such multiplication ofvalve structures not only increases the space requirements butcomplicates the problem of adjusting the several distinct valves so theywill function in proper coordinated fashion.

SUMMARY OF THE INVENTION It is a primary object of this invention toprovide a fluid motor control system that will be compact and provideready and accurate adjustment to assure proper coordinated functioningof the several flow control elements.

This end is effected for the most part by the provision of a four-waymotive fluid supply or main valve having respective motive fluid inletand outlet chambers and a pair of motor chambers connected to theopposite ports of the fluid motor and respectively connected at theiropposite ends to the fluid inlet and outlet chamber through respectivefluid pressure responsive valves opening in the direction of flowtherethrough and operable in opposing paired relation by a simpledouble-poppet pilot valve so as to supply motor fluid at a selected rateto the motor from the selected motor chamber to establish the directionand speed of operation of the fluid motor. The pressure-responsivevalves are in essence mere piston-type shut off valves movable to andfrom closed position by fluid pressures directed onto the piston fromwithin the body of the main valve, for example, of the general typeshown in U.S. Pat. No. 2,841,359 of William F. Berck issued July l,1958. In using such pressure-responsive valves in the manner suggestedabove, the respective pressure-responsive valves controlling fluid flowto the motor chambers of the supply valve will be subjected to fullmotor inlet fluid pressure in an opening direction while thepressure-responsive valves controlling fluid flow from the motorchambers of the supply valve will be subjected to the always lessermotor outlet fluid pressure in an opening direction. As a consequence,the inlet chamber valve at all times will be more open" than the outletchamber valve insuring that only one valve of the paired operatingvalves will regulate flow and that valve oscillations or hunting" isprevented.

It is another important object of the present invention to provide afour-way valve having (I) a first body section of generally figure eightconfiguration formed to provide side-byside end abuttingnoncommunicating motor chambers having a common overlying inlet chamberwith a centered flanged inlet port along one face communicating with therespective motor chambers through ported valve seats facing toward theother face of said first body section which is apertured in coaxialrelation to said valve seats and mounts therein respective removablenormally closed, pressure-responsive valve assemblies for controllingfluid flow from the inlet chamber to the respective motor chambers whichhave respective flanged motor connection ports at the opposite ends ofthe first body section and (2) a second body section formed to providean outlet chamber superposed upon and communicating with said respectivemotor chambers through ported valve seats facing toward the opposingface of said second body section which is apertured in coaxial relationto the last mentioned valve seats and mounts therein respectiveremovable, normally closed pressure-responsive valve assemblies forrespectively controlling fluid flow from the motor chambers to theoutlet chamber which is provided with a flanged outlet port.

A further object of the present invention resides in providing a pilotcontrol valve for controlling the operation of the pressure-responsivevalve assemblies of the first object comprising an elongated valve bodyhaving a through bore enlarged at its opposite ends to form respectiveoppositely facing valve seats at the inner ends of the end enlargements,respective inlets leading inwardly from an outer wall face to the endenlargements, outlet means leading from an outer wall face to thethrough bore between valve seats, respective poppet valves guided formovement in said through here between their normally closed positionseated on the oppositely facing valve seats to prevent fluid passagefrom the respective inlets to the outlet means, actuator means disposedin the through bore between the adjacently related ends of therespective poppets, and manually operable handle means drivinglyconnected to the actuator means and adapted upon selective rockingmovement in opposite directions to shift one or the other of the poppetsfrom its seat toward open position thereby initiating throttled flow offluid from the selected inlet to the outlet means.

Still another object of the present invention resides in providing themain valve of the first object with a normally open needle valvecontrolled bypass connection between the outlet chamber and one of themotor chambers to prevent the formation of a vacuum in the motor loopand assure a source of oil to maintain the motor loop filled when themotor loop is closed off by closing off the main supply valve and theoil cools down and contracts.

A still further object of the present invention resides in providingrespective sets of external pipe for connecting the main supply valve ofthe second object to the pilot control valve of the third object to formthe system of the first object, each of said respective sets of externalpipe comprising a T- fitting having an inlet connected through a valvecontrolled line to the main supply valve inlet chamber and its otherconnections respectively connected by a straight open line to one of thepilot valve inlets, and by respective valve controlled branch lines tothe downstream side of the pressure-responsive valve assembly leading toone of the motor chambers, and to the downstream side of the pressureresponsive valve assembly leading from the other motor chamber wherebythe required adjustments of pressure can be effected to assure that thepressure applied to the downstream side of the operatingpressure-responsive valves at full opening of the pilot control valveapproximates the exhaust pressure in the supply valve exhaust chamberand that the flow of fluid to and from the pressure responsive valvescan be varied to obtain the desired rate of valve response.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects of the presentinvention will appear from the following description and appended claimswhen read in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view illustrating the simplified motor controlsystem provided when employing the four-way motor control valve of thepresent invention;

FIG. 2 is a schematic view illustrating the varying flow paths and theirrespective adjustments provided by the motor control system of thisinvention;

FIG. 3 is a longitudinal vertical section view through the manuallyoperable pilot valve of FIG. 1 taken substantially along line 3-3 ofFlG.1;

FIG. 4 is a transverse sectional view through the manually operablepilot valve of FIG. 3 taken substantially along line 4-4 of FIG. 3;

FIG. 5 is an elevational view of the four-way motor control valve ofFIG. 1 as viewed from the side of FIG. 1 opposite that containing theinlet and outlet port connections; and

FIG. 6 is an elevational view of the four-way motor control valve ofFIG. 1 as viewed from the side: of FIG. 1 containing the motor supplyport connection.

DESCRIPTION OF PREFERRED EMBODIMENT With continued reference to thedrawings where the same reference numerals are employed throughout theseveral FIGURES of the drawings to indicate the same parts, the presentinvention provides a fluid motor control assembly of unusual simplicityand compactness predicated on the employment of primary fluid controlvalve of novel construction for channelling and controlling the rate offlow of the driving fluid to and from the fluid motor 21 under manualcontrol of an operator at a deck stand 22 provided with a manuallyoperable direction and speed control pilot valve 23. While fluid motor21 may be of any conventional construction, for example, one of the RotoCycle" motors marketed by the assignee of this application, RockwellManufacturing Company, and illustrated generally by the disclosure ofthe aforementioned US. Pat. No. 2,913,990 of CR. Taylor, primary valve20 and speed control pilot valve 23, both of novel construction, will behereinafter described in detail.

Referring for the moment t to the schematic illustrations of FIG. 2 andthe general perspective view of FIG. 1, the control system of thisinvention, predicated on the construction and assembly of valves.20 and23 and their connections to fluid motor 21 and each other, will now bedescribed. Driving fluid, usually oil from a suitable pump and supplysource not shown, enters fluid control valve 20 through flanged inletport 25 leading into an inlet chamber 26 (FIG. 2) of main valve body 27delimited opposite inlet port 25 by a partition wall 28 (FIGS. 2 and 6)defining a pair of laterally spaced flow passages 29 respectivelyleading from inlet chamber 26 into a first section of main valve body 27the two loops of which respectively define laterally spacednoncommunicating motor chambers 32 and 34; motor chamber 32 has aflanged motor connection port 33 right angularly related to flangedinlet port 25, and motor chamber 34 has a flanged motor connection port35 right angularly related to flanged port 25. As best seen from aninspection of FIGS. 5 and 6, the horizontal axes of port 25 and flowpassaged 29 lie in a lowermost common horizontal plane while thehorizontal axes of ports 33 and 35 lie in a common horizontal planespaced above the plane of the uppermost portion of passages 29. Theupper sidewalls of chambers 32 and 34 are formed to provide upwardlydirected tubular passages 36 (FIGS. 1 and 5) defining respective flowpassages 37 (FIG. 2) leading from chambers 32 and 34 to a second uppersection of main valve body 27 defining an outlet chamber 38 (FIG. 2)having a flanged outlet port 39 lying in vertically space d relationabove flanged inlet port 25 (FIGS. 1 and 6) with its axis in a commonvertical plane with the axis of flanged inlet port 25 and centeredlaterally with respect to the loop portions of the second or upper valvebody section and the flow passages 37 of the first or lower valve bodysection. The top wall 41 of the upper valve body section in coaxiallyopposed relation to flow passages 37 and the end wall 42 of the lowervalve body section in coaxially opposed relation to flow passages 29 areformed with through apertures 43 rimmed by outwardly directed annularbosses 44 (FIGS. 1, 5 and 6). Bosses 44 are provided with axiallydirected, angularly spaced tapped apertures (not shown) mountingattachment studs 45 removably mounting respective pressure-responsivevalve assemblies 46 for controlling the fluid flow through passages 29and 37. Since each of these assemblies 46 is identical and operates inprinciple like the removable assembly of the aforesaid US. Pat. No.2,841,359 to W.F. Berck, it is sufficient to state that each comprises acylindrical body 47 of a length to span the depth respectively of motorchambers 32 and 34 and outlet chamber 38. Each cylindrical body 47 isclosed at its outer end by flanged end wall 48 and is provided withexternal O-ring grooves and O-rings 49 in position to sealingly engagewithin flow passages 29, 37 and the through apertures 43 to confinefluid flow from inlet chamber 26 to motor chambers 32, 34 and from motorchambers 32, 34 to outlet chamber 38 to entering the inner ends ofcylindrical bodies 47 through removable seat ring 50 held in place by aconventional split retainer ring'and passing outwardly through sidewallports 51 of bodies 47 when the normally closed valve elements 52, 53, 54and 55 are selectively unseated. The valve elements are selectivelyunseated in operative pairings 52--55 or 53--54 to connect the motorloop composed of motor chamber 32, motor pipe 56 and motor 21, motorpipe 57 and motor chamber 34 to the pump loop composed of outlet chamber38, pump inlet 58, a fluid pump (not shown) pump outlet pipe 58, andinlet chamber 26 through a selected valve pair, for example 5255 shownin their open positions by dotdash lines in FIG. 2. i

Selective operation of pressure-responsive valve elements 52 through 55is accomplished in accord with the present invention by the combinedclosing biasing force of a closing spring 61 seated at one end in thecavity provided by the rearwardly directed skirts of valve elements 52through 55 and the controlled application of fluid pressure to thecavities of the respective valve elements through centered ports 62provided in the respective end walls 48 of cylindrical bodies 47 ofvalve assemblies 46. While any available fluid pressure source could beemployed, the present invention contemplates the use of the pressureenergy of the motive fluid at the valve inlet chamber 26 which, it willbe appreciated, will provide without need for complicated controlequipment consistently higher opening force on valve elements 52 and 53than is available in the valve outlet chamber 38 acting to open valveelements 54 and 55. This natural pressure differential is used toadvantage by reason of the novel four-way control valve of the presentinvention which assures an identical opening force (valve inletpressure) acting on the fluid inlet valve elements 52, 53 and anidentical but proportionally lower opening force (valve outlet pressuredetermined solely by the pressure loss due to work done in driving motor21 and conveying the motor fluid through the motor loop) acting on valveelements 54 and 55. Any variation in the valve inlet pressure willeffect a corresponding variation in the valve outlet pressure and thebiasing force applied to maintain valve elements 52 through 55 normallyclosed. To provide the desired response of the respective valve elements52 through 55 upon actuation of the pilot control valve 23 to behereinafter described in detail, the present invention provides twoseparate and distinct control circuits 63 and 64 FIGS. 1 and 2)respectively pairing valve elements 52, 55 and valve elements 53, 54 forcojoint operation. While either control circuit may be connected tocontrol flow to the fluid motor inlet 65 or the fluid motor outlet 66,the inlet 65 is shown in FIG. 1 to be connected by pipe 56 to flangedport 33 of motor chamber 32 and the outlet 66 is shown in FIG. 1 to beconnected by pipe 57 to flanged port 35 of motor chamber 34. The motorinlet circuit, therefore, is controlled by valve elements 53, 54operation of which is effected by control circuit 64 while operation ofvalve elements 52, 55 to supply motor fluid through the motor outletcircuit to reverse motor 21 is effected by control circuit 63. Sinceboth control circuits 63, 64 are identical a description of one onlywill be given here.

Referring for the moment to control circuit 64, which will be referredto hereinafter as the motor inlet control circuit, it comprises a supplypipeline 71 (FIGS. 1 and 2) connected at one end through a tapped boss70 and a T-fltting 73 (FIG. 6) to the inlet chamber 26 of control valve20. A similar T-fitting 73 is connected to the corresponding supplypipeline of control circuit 63 referred to hereinafter as the motoroutlet control circuit. Supply pipeline 71 includes a variablerestriction, preferably in the form of a manually adjustable needlevalve 72, and leads through a T-connection 73 to one of the inlets 74FIGS. 1, 2 and 3) of pilot control valve 23. T-connection 73 has abranch supply line 75 connected thereto to divert a portion of the fluidflow through supply line 71 for use in applying pressure to the cavitiesof valve elements 53 and 54. To this end branch supply line 75 leadsthrough a T-connection 76 to a manually adjustable needle valve 77threaded into tapped port 62 in end wall 48 of the upper right handvalve assembly 46 (FIGS. 1 and 5) containing valve element 54 to applythe line pressure (inlet chamber pressure so long as pilot control valve23 remains in its normal off or closed position) to the cavity of valveelement 54 to aid its spring 61 in normally maintaining valve element 54firmly in its fully closed position. A portion of the flow throughbranch supply line 75 is diverted by Tcnnection 76 into a through branchsupply line 78 and adjustable needle valve 79 threaded into tapped port62 in end wall 48 of the lower left hand valve assembly 46 (FIGS. 1 andcontaining valve element 53 to apply the same line pressure to itscavity to aid its spring 61 in normally maintaining valve element 53firmly in its fully closed position. The corresponding supply lines 81,82 and 83, connected through corresponding T-connections 73 and 76 andcorresponding needle valves 72, 77 and 79, connect valve inlet chamber26 respectively to the other inlet 84 (FIGS. 1, 2, and 3) of pilotcontrol valve 23, to the cavity of valve element 55 of the upperleft-hand valve assembly 46, and to the cavity of valve element 52 ofthe lower right-hand valve assembly 46 in the same manner to normallymaintain valve elements 52 and 55 firmly in their fully closedpositions.

Under normal operation conditions with pilot control valve 23 in itsintermediate "ofF position (FIG. 3), the full inlet chamber pressurewill be effectively applied to the chambers 85 and 86 surrounding thepiston sections 87 of the respective poppets 88 and 89 of pilot controlvalve 23 but will have little, if any, effect of sealing the poppets dueto the minimum upstream area of the poppets exposed to the pressure andthe combined opposing areas of the poppets and the opposing area ofO-ring bearing groove and ring formations 91 provided on the pistons 87to guide and seal the piston ends of the poppets in the cylinderchambers 92 formed in the flanged valve body end closure caps 93 boltedto the end faces of body 94 and provided to close and seal the outerends of the respective chambers 85 and 86. Suitable O-ring groove andring formations 91 in the ends of body 94 seal caps 93 against fluid andpressure leakage from the chambers. As best seen from an inspection ofFIGS. 3 and 4, the valve body 94 of pilot control valve 23 comprises anelongated block of generally square configuration in cross sectionhaving a concentric longitudinally extending bore 95 of lesser diameterthan chambers 85 and 86 interconnecting end chambers 85 and 86 andforming inwardly directed annular shoulder defining sharp sealingcorners 96 at the inner ends of chambers 85 86. Body 94 intermediate itsends and below bore 95 is provided with a blind stepped bore 97 disposedat right angles to the axis of bore 95 and at opposite sides of steppedbore 97 is drilled inwardly to provide outlet ports 98 intersecting bore95 adjacent but inwardly from sealing corners 96. Each of the poppets 88and 89 at the inner end of piston sections 87 is enlarged in diameter toform an annular flange 100 beyond which the main body 99 is formed as ahemisphere merging into a stem portion 101 trailing on annular discliketerminal guide portion 102 having a sliding fit in bore 95. As best seenfrom FIG. 3, stern portion is of such length that guide portion 102 inthe normal closed position of poppets 88 and 89 lies only slightlybeyond the intersection of outlet ports 98 with bore 95 assuring a freeopen intermediate area of bore 95 above and at opposite sides ofright-angularly related stepped bore 97. The innermost end 103 ofstepped bore 97 (FIG. 4) forms a journal for the inner reduced diameterend 104 of a rack pinion shaft 105 the drive pinion 106 of which isdisposed adjacent joumaled end 104 in the enlarged diameter portion 107of stepped bore 97 lying immediately below and intersecting bore 95sufficiently to as sure meshing of pinion 106 with the downwardlyprojecting rack teeth 108 formed by chordally slotting the periphery ofcylindrical actuator plunger 109 dimensioned for free sliding movementalong bore 95 between the inner poppet guide portions 102. Shaft 105,immediately outwardly of pinion 106, is reduced in diameter below theroot diameter of the teeth of pinion 106, then provided with an enlargedjournal section 112 angularly grooved at 111 to receive an O-ring seal113 engage'able with the through bore of laterally flanged journalsleeve 114 bolted to the side face of body 94 in sealing engagement withan O-ring 113 on the clamp shoulder of bore 97 and a reduced diameterend 115 cross bored to receive a roll pin 116 or the like for fixing thehub 117 of a manually operable actuating handle 118 to the outer end ofshaft 105. Actuator plunger 109 is longitudinally through drilled andtapped at 120 to receive hollow NYLOK socket headed adjustment screws121 adapted to be threaded in and out as required to preset the pickuppoint of the respective poppets 88 and 89 and assure full opening andclosing of the poppets within the operative stroke of handle 118. Itwill also be noted that the stem portions of poppets 88 and 89 arethrough drilled at 122 so free fluid circulation is permitted from endto end of the poppets as well as the actuator plunger 109 therebyassuring relatively free shuttling of both the actuating plunger 109 andthe respective poppets 89 back and forth through whatever fluid may bepresent in chambers 85, 86, bore 95 and chambers 92 under manual openingoperating of lever 118 and spring-closing movement under influence ofbiasing springs 123 acting between end closure caps 93 and the taperedbottom wall of piston sections 87.

Operation of the fluid motor control system just described is effectedto supply motive fluid to motor 21, through motor port 65 by shiftinglever 118 clockwise: as viewed in FIGS. 1 and 2 from the position ofFIG. 2 to the position of FIG. 1. Such clockwise movement rotates rackpinion 106 counterclockwise as seen in FIG. 3 shifting actuating plunger109 partway toward chamber 85 connecting fluid inlet 74 to outlet port98 adjacent chamber 85 and establishing fluid flow through pipelinecontrol circuitry 64, inlet 74 and its related outlet port 98, thecommon outlet chamber 131 and outlet pipe 132 to outlet chamber 38. Flowof fluid through circuitry 64 as just described is assured since inletchamber 26 is connected through flanged inlet port 25 and pipe 58 (seeFIG. 1) to the outlet or high-pressure side of the fluid supply pump,outlet chamber 38 is connected through flanged outlet port 39 and pipe59 (see FIG. 1) to the inlet or low-pressure side of the fluid supplypump, and the higher pressure side of the fluid supply pump, and thehigher pressure prevailing on the upstream side the actuated poppet 88will effect such directional flow at the rate determined by the openposition of the actuated poppet so long as the pressure differentialdescribed remains. Immediate flow from chamber 26 through valve closuremember 53 to motor chamber 32 and to motor 21 through pipe 56 will nottake place, however, since pressureresponsive valve assemblies 46containing valve closure members 53 and 54 under control of circuitry 64is throttled through needle valves 79 and 77 respectively to establish adesired responsiveness of the respective valves. The delay, however, iscustomarily a short delay sufficient only to avoid a rapid buildup ofthe final closing biasing force that might cause hammering" in theoverall fluid system. As soon as the flow past the actuated poppet 88has been sufficient to establish a reduction to the total closingbiasing force below the total opening force exerted on the valve closingmembers 53 (full outlet pump pressure) and 54 (pump inlet or motor looppressure), valves 53 and 54 will move toward full open position to aposition at which the biasing force (combined force of the spring 61 andthe lower pressure in inlet chamber 26 on valve 53) balances the loweredpressure in inlet chamber 26 established by the rate of flow past valveclosure member 53. Unless the actuated poppet 89 is further opened ormoved toward its closed position, the fluid system will reach a point ofequilibrium where the biasing force (spring and fluid pressure combined)on valve closure members 53 and 54 established by the fluid flow throughcontrol circuitry 64 under influence of the pump outlet pressure inchamber 26 balances the opening force (pressure differential on theupstream side of the respective valve closure members 53 and 54established by the related operating pressures in chambers 26 and 34).Since the motor outlet pressure in valve outlet chamber 38 is alwaysappreciably lower than the pump outlet pressure in valve inlet chamber26 and as both valves 53 and 54 have the same biasing force actingthereon, the inlet valve 53 (or inlet valve 52 when control circuitry 63is operating will be open more than outlet valve 54 (or outlet valve 55when control circuitry 63 is operating). It is thus assured that onlyone valve, the outlet valve, effects flow regulation when flow isestablished. It follows, therefore, that the operated valve pairs 53, 54or 52, 55 are prevented from interacting with each other and hunting iseliminated. Furthermore since no flow is permitted by the other poppet89 cooperating with control circuitry 63, full pump outlet pressure (thefluid pressure of chamber 26) is maintained on the opposing valve pair(valves 52, 55) assuring that they are maintained fully closed.

When pilot valve handle 118 is restored to its off position flow throughcontrol circuit 64 is promptly blocked at the outlet end of chamber 85by closing of poppet 89 under influence of spring 123 and any upstreampressure differential that may be effective to act on poppet 89. Thepressure in control circuit 64 then builds up gradually until thebiasing force on valve closure members 53 and 54 (spring force plus therising fluid pressure in control circuit 64 approaching pump pressure ininlet chamber 26 times downstream area of the valve closures) exceed theopening force (inlet chamber pressure times the upstream area of valveclosure member 53 and outlet chamber pressure times the upstream area ofvalve closure member 54) effecting a closing of valve closure members 53and 54 and throttling of fluid flow past valve closure members 53 and 54in accord with the closing movement of poppet 89. Once closed the motorloop and pump loop will be fully isolated from each other by firmlyclosed valve closure members 53 and 54 and cooling of the motive fluidin the motor loop and the resulting contraction of the volume of motivefluid may create a vacuum causing air to enter the motor loop. Toprevent this the present invention contemplates a bypass pipe connection133 (FIGS. 1, 2 and between the valve outlet chamber 38 and one of thevalve motor chambers, chamber 34 in the present illustration, so oilfrom the pump loop will be available to enter the motor loop uponcooling of the oil to avoid the entry of air into the system. Bypassconnection 133 is provided with a manually operable needle valve 79permitting, when closed, a check operation to verify proper valveseating when necessary. Also the end closure caps 93 of pilot valve 23are preferably provided with centered tapered through bores 134 tappedto receive pipe plugs 135 to bleed air and drain pilot valve 23 duringinitial setting up of the system.

Similar air bleed plugs 135 are provided in the end walls 48 of theupper pressure-responsive valve assemblies 46 (FIGS. 5 and 6) to bleedair from the valve body 27 during the initial setting up of the system.Also to aid in removal of the pressure-responsive valve assemblies 46for servicing and replacement when necessary the end closure walls arethrough drilled and tapped at spaced points between studs 45 to receivejacking screws 136 FIGS. 5 and 6) arranged to bear upon the end faces ofannular bosses 44 to effect initial axial withdrawal of the respectiveassemblies 46.

What I claim and desire to be secured by Letters Patent is:

1. Control mechanism for fluid pump and a rotary fluid motor systemcomprising a main valve means for varying the rate and direction of flowof driving fluid through the fluid motor comprising a valve bodydefining an inlet port and chamber adapted for connection to the fluidpump outlet and an outlet port and chamber adapted for connection to thefluid pump inlet, a pair of motor chambers having respective portsadapted for connection to the opposite sides of the fluid motor,respective inlet passages communicating with said inlet chamber andrespective outlet passages communicating with said outlet chamber;respective pressure-responsive valve assemblies mounted in said motorchamber inlet passages and said motor chamber outlet passages inrespective coaxial operative downstream relation providing valve closuremembers movable between normally closed and open valve positions inresponse to an effective overriding upstream fluid pressure each of saidvalve closure members having upstream and downstream sides isolated fromone another; respective biasing means normally biasing said valveclosure members to normally closed position, said biasing meansincluding a manually operable pilot valve having respective fluid portsconnected through respective central circuits having communicatingbranch lines to the inlet port of said main valve means, to thedownstream side of one of said valve closure members controlling-fluidflow from said inlet chamber to one of said motor chambers, and to thedownstream side of said valve closure member controlling fluid flow fromthe other of said motor chambers, and at least one outlet connected tosaid outlet port of said main valve means said communication beingupstream of said pilot valve, and said manually operable pilot valvealso having respective pressure-responsive valve means selectivelymanually shiftable from a normal position blocking flow through saidpilot valve inlets to said at least one outlet and maintaining full mainvalve inlet chamber fluid pressure on all of said valve closure membersto varying open positions venting said respective branch lines to saidoutlet chamber of said main valve thereby establishing pressuredifferentials on the selected pair of valve closure members in accordwith the open position of said shifted valve means of said pilot valveto control the direction and rate of flow of driving fluid to said fluidmotor.

2. The control mechanism of claim 1 wherein the respective branch lineconnections between the fluid inlet port and the downstream sides of therespective operating pairs of fluid responsive valve members and therespective inlets of the manually operable pilot valve comprise externalpiping including a main line leading to a junction providing a firstbranch leading to one inlet of said pilot valve, a second branch leadingto the inlet port pressure-responsive valve of one of said motorchambers and a third branch leading to the outlet pressure responsivevalve of said other motor chamber passage.

3. The control mechanism of claim 2 wherein said main line is providedwith a variable restriction enabling adjustment of the pressure appliedthrough said second and third branch at full venting position of saidmanually operable pilot valve to approximate the pressure at the mainvalve outlet port.

4. The control mechanism of claim 3 wherein said second and third branchlines are each provided with a variable restriction enabling the flow offluid therethrough to be controlled to control response of therespective pressureresponsive valves.

5. The control mechanism of claim 1 wherein said respectivepressure-responsive valve means in said manually operable pilot valvecomprises a double-poppet valve providing a normally spring-closedpoppet for each of said inlets and actuating means disposed between saidpoppets in normal blocking position and including handle means movablein opposite directions only and adapted upon movement of said handlemeans in a selected direction to engage and unseat the selected poppetand move it to progressively increased venting positions as said handlemeans is moved in the selected direction.

6. The control mechanism of claim 1 wherein one of the motor chambers ofsaid main valve is connected through a normally open needle valvecontrolled line connection to the main valve outlet chamber therebyproviding a bypass connection between the motor loop and the controlvalve outlet port to prevent the formation of a vacuum in the motor loopand entry of air into the motor loop upon cooling of the operating oilin the motor loop when the control valve is in fully closed position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,584,539 Dated June 15 1971 Inventor(s) H rry Sugden, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below: (Since theline numbering in the patent is off from 1 to 6 or 7 lines in places,the following corrections are noted with respect to the actual linecount in each column.)

Colunm 1, line 50, insert a comma after "side".

Column 1, line 56, insert a comma after "removable".

Column 2, line 56, change "section" to sectional Column 3, line 19,after "moment" delete the "t".

Column 3, line 37, change "passaged" to passages Column 4, line 43,before "Figures" insert an opening parenthesis.

Column 4, line 67, before "Figures" insert an opening parenthesis Column5, line 7, change "a" to and Column 5, line 27, change "of" to on Column5, line 44, after "85" insert and Column 5, line 53, change "on" to anColumn 6, line 18, change "operating" to operation Column 6, lines 38and 39, delete "and the higher pressure side of the fluid supply pump".

Column 6, line 40, after "side" insert of FORM Po-wso (\o-se) USCOM DC60 M 376-P59 US GOVERNMENT PRINTING OFFICE I969 O-ElGl-JII V UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,584,539 DaJune 15, 1971 Inventor(s) r y S g n, Jr. PAGE 2 It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 6, line 54, change "to" to of Column 6, line 62, change "89" to88 Column 7, line 2, after "operating" insert closing parenthesis Column7, line '15,, change "89" to 88 Column 7, line 17, change "89" to 88Column 7, line 22, change "exceed" to exceeds Column 7, line 21, change"89" to 88 Column 7, line 53, before "Figures" insert open parenthesis,

Column 7, line 57, insert a after "for".

Column 8, line 9, change "central" to control Signed and sealed this lth day of March 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK I Attesting Officer 7Commissioner of Patents FORM PO-IO5O (10-59) USCONHWDC eo376 P6g U 5,GOVERNMENT PRINTING OFFICit 5! 0*365334

1. Control mechanism for fluid pump and a rotary fluid motor systemcomprising a main valve means for varying the rate and direction of flowof driving fluid through the fluid motor comprising a valve bodydefining an inlet port and chamber adapted for connection to the fluidpump outlet and an outlet port and chamber adapted for connection to thefluid pump inlet, a pair of motor chambers having respective portsadapted for connection to the opposite sides of the fluid motor,respective inlet passages communicating with said inlet chamber andrespective outlet passages communicating with said outlet chamber;respective pressure-responsive valve assemblies mounted in said motorchamber inlet passages and said motor chamber outlet passages inrespective coaxial operative downstream relation providing valve closuremembers movable between normally closed and open valve positions inresponse to an effective overriding upstream fluid pressure each of saidvalve closure members having upstream and downstream sides isolated fromone another; respective biasing means normally biasing said valveclosure members to normally closed position, said biasing meansincluding a manually operable pilot valve having respective fluid portsconnected through respective central circuits having communicatingbranch lines to the inlet port of said main valve means, to thedownstream side of one of said valve closure members controlling fluidflow from said inlet chamber to one of said motor chambers, and to thedownstream side of said valve closure member controlling fluid flow fromthe other of said motor chambers, and at least one outlet connected tosaid outlet port of said main valve means said communication beingupstream of said pilot valve, and said manually operable pilot valvealso having respective pressure-responsive valve means selectivelymanually shiftable from a normal position blocking flow through saidpilot valve inlets to said at least one outlet and maintaining full mainvalve inlet chamber fluid pressure on all of said valve closure membersto varying open positions venting Said respective branch lines to saidoutlet chamber of said main valve thereby establishing pressuredifferentials on the selected pair of valve closure members in accordwith the open position of said shifted valve means of said pilot valveto control the direction and rate of flow of driving fluid to said fluidmotor.
 2. The control mechanism of claim 1 wherein the respective branchline connections between the fluid inlet port and the downstream sidesof the respective operating pairs of fluid responsive valve members andthe respective inlets of the manually operable pilot valve compriseexternal piping including a main line leading to a junction providing afirst branch leading to one inlet of said pilot valve, a second branchleading to the inlet port pressure-responsive valve of one of said motorchambers and a third branch leading to the outlet pressure-responsivevalve of said other motor chamber passage.
 3. The control mechanism ofclaim 2 wherein said main line is provided with a variable restrictionenabling adjustment of the pressure applied through said second andthird branch at full venting position of said manually operable pilotvalve to approximate the pressure at the main valve outlet port.
 4. Thecontrol mechanism of claim 3 wherein said second and third branch linesare each provided with a variable restriction enabling the flow of fluidtherethrough to be controlled to control response of the respectivepressure-responsive valves.
 5. The control mechanism of claim 1 whereinsaid respective pressure-responsive valve means in said manuallyoperable pilot valve comprises a double-poppet valve providing anormally spring-closed poppet for each of said inlets and actuatingmeans disposed between said poppets in normal blocking position andincluding handle means movable in opposite directions only and adaptedupon movement of said handle means in a selected direction to engage andunseat the selected poppet and move it to progressively increasedventing positions as said handle means is moved in the selecteddirection.
 6. The control mechanism of claim 1 wherein one of the motorchambers of said main valve is connected through a normally open needlevalve controlled line connection to the main valve outlet chamberthereby providing a bypass connection between the motor loop and thecontrol valve outlet port to prevent the formation of a vacuum in themotor loop and entry of air into the motor loop upon cooling of theoperating oil in the motor loop when the control valve is in fullyclosed position.